| 摘要 |
Heat stable, easily processable vinyl chloride polymers are prepared by polymerizing in aqueous emulsion a monomer mixture of 70 to 100% by weight of vinyl chloride and 0 to 30% by weight of at least one other monoethylenically unsaturated monomer in water with agitation in the presence of a water-insoluble soap as the sole emulsifier. Many suitable comonomers are specified including halogen-substituted olefins; vinyl, allyl and isopropenyl esters and ethers; olefins and vinyl aromatic compounds; maleic, fumaric, acrylic and methacrylic esters and nitriles; and vinylidene cyanide. The soaps are water-insoluble salts of lithium and polyvalent metals with saturated, unsaturated and substituted fatty acids, e.g. the beryllium, barium, calcium, magnesium, strontium, cadmium, zinc, lead, tin, titanium and aluminium salts of octanoic, stearic, oleic, linoleic, ricinoleic, palmitic and abeitic acids, and the polyvalent metal salts of organic sulphates, e.g. barium lauryl sulphate. Polymerization may be effected in the presence of actinic radiation or free radical initiators, e.g. azo compounds, hydrogen peroxide, alkali metal and ammonium persalts, alkyl borane peroxide and conventional redox systems; and buffers, e.g. ammonia, ammonium bicarbonate and sodium bicarbonate. The soap may be formed in situ. Examples describe the emulsion polymerization in the presence of potassium persulphate and ammonia of (I) vinyl chloride using barium laurate; (II) vinyl chloride using barium laurate, stearate or myristate formed in situ from barium hydroxide and lauric, stearic or myristic acids; (III) vinyl chloride and methyl acrylate using barium laurate; (IV) vinyl chloride and vinyl acetate using barium laurate; (V) vinyl chloride using aluminium stearate, cadmium stearate, calcium stearate, calcium laurate, lead stearate, magnesium stearate, magnesium laurate or stannous stearate; (VI) vinyl chloride using barium lauryl sulphate; and (VII) vinyl chloride using lithium laurate, lithium stearate or lithium myristate; and the polymerization in the presence of potassium persulphate and sodium bicarbonate of (V) vinyl chloride using cadmium stearate, calcium laurate or magnesium stearate. The latices formed may be coagulated or spray dried and the products compounded with plasticizers, e.g. dioctyl phthalate, to give plastisols. Specifications 599,429, 627,265, 637,395, 652,069, 698,359, 699,016, 865,651 are referred to. |
